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sier: get zoom down to 122 bytes

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This commit is contained in:
Vince Weaver
2021-03-01 19:39:49 -05:00
parent 9e83c5498f
commit 20222ea913
1 changed files with 20 additions and 14 deletions
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34
graphics/gr/sier/sier.s
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@@ -17,11 +17,15 @@
; 140 bytes -- bot demo version ; 140 bytes -- bot demo version
; 137 bytes -- remvoe & jump ; 137 bytes -- remove & jump
; 135 bytes -- init with HGR, which sets A=0 ; 135 bytes -- init with HGR, which sets A=0
; 133 bytes -- remove ldx #0 in paeg flip code ; 133 bytes -- remove ldx #0 in page flip code
; 130 bytes -- load in zero page ; 130 bytes -- load in zero page
; 128 bytes -- init T_L, T_H as part of zero page since we live there ; 128 bytes -- init T_L, T_H as part of zero page since we live there
; 126 bytes -- shorter 16-bit increment of T_L
; 122 bytes -- use trick of jumping mid-PLOT for MASK calculation
; LoveByte requires 124 bytes
; zero page ; zero page
@@ -90,21 +94,25 @@ sier_yloop:
txa ; YY ; plot call needs Y/2 txa ; YY ; plot call needs Y/2
lsr lsr
bcc even_mask php
ldy #$f0
.byte $2C ; bit hack ; bcc even_mask
even_mask: ; ldy #$f0
ldy #$0f ; .byte $2C ; bit hack
sty MASK ;even_mask:
; ldy #$0f
; sty MASK
jsr GBASCALC ; take Y-coord/2 in A, put address in GBASL/H ( a trashed, C clear) jsr GBASCALC ; take Y-coord/2 in A, put address in GBASL/H ( a trashed, C clear)
lda GBASH lda GBASH
draw_page_smc: draw_page_smc:
adc #0 adc #0
sta GBASH ; adjust for PAGE1/PAGE2 ($400/$800) sta GBASH ; adjust for PAGE1/PAGE2 ($400/$800)
plp
jsr $f806 ; trick to calculate MASK by jumping
; into middle of PLOT routine
; reset XX to 0 ; reset XX to 0
@@ -112,7 +120,6 @@ draw_page_smc:
sty XX_TL sty XX_TL
sty XX_TH sty XX_TH
sier_xloop: sier_xloop:
; want (YY-(XX*T)) & (XX+(YY*T) ; want (YY-(XX*T)) & (XX+(YY*T)
@@ -172,9 +179,9 @@ green:
blah_smc: blah_smc:
adc #1 adc #1
sta T_L sta T_L
lda T_H bcc no_carry
adc #0 inc T_H
sta T_H no_carry:
; speed up the zoom as it goes ; speed up the zoom as it goes
inc blah_smc+1 inc blah_smc+1
@@ -192,7 +199,6 @@ done_page:
eor #$4 ; flip draw page between $400/$800 eor #$4 ; flip draw page between $400/$800
sta draw_page_smc+1 ; DRAW_PAGE sta draw_page_smc+1 ; DRAW_PAGE
jmp sier_outer ; what can we branch on? jmp sier_outer ; what can we branch on?
T_L: .byte $00 T_L: .byte $00